because of her family name i suppose! it's not the same for woman than for for the men like everywhere sadly :(
And she was always compared to her sister so for them she was ugly compared to Irene! But we know she Is beautiful and to top it all she has mana and all! If the real daugther had been loved from the start she shouldn't have been hurt so much and made so much mistake
I think because in the first chapter, she mentioned that all of the other children were perfect, allrounder, kindhearted etc but Sylvia was a "misprint". And the adults' comments towards her were how she was gloomy and in a daze or something. So maybe, it's most likely because of Sylvia's personality and how she's not smart nor confident like her siblings. So even though her looks aren't bad, maybe to them she wasn't as perfect as the others.
Damn I don't understand.... The brother who came to scold her in her room looks exactly just like her but apparently no one is saying shit about his looks so wtf were they saying it about hers even before she starts eating too much ???
The hair color isnt exactly the same but you can easily guess that they're siblings